Plating method and method of manufacturing printed circuit board

ABSTRACT

In a plating method, a laminate made of stainless steel, and copper or a copper alloy is prepared. Plating underlayers made of nickel are formed on a first plated portion provided at the stainless steel and a second plated portion provided at the copper or the copper alloy at the same time with use of a hydrochloric acid electrolytic solution.

BACKGROUND Technical Field

The present invention relates to a plating method and a method ofmanufacturing a printed circuit board.

Description of Related Art

A laminate in which different types of metals are laminated may be usedas an electronic product. For example, in a printed circuit board usedin a drive device such as a hard disc drive device, a stainless steelplate and a conductor layer made of copper or a copper alloy are formedwith an insulating layer provided therebetween. A plating process isexecuted on predetermined portions of the stainless steel plate and theconductor layer, so that a printed circuit board is manufactured (see JP2014-210959 A, for example.).

It is preferable that the plating process is executed on the stainlesssteel plate and the conductor layer at the same time. However, a passivefilm is formed on the surface of the stainless steel plate. Therefore,it is not easy to execute the plating process on the stainless steelplate and the conductor layer at the same time.

In JP 2014-210959 A, before the plating process for the stainless steelplate, a voltage is applied between the stainless steel plate and anelectrode such that the stainless steel plate serves as an anode and theelectrode in a plating layer serves as a cathode. In this case, thepassive film formed on a plated portion is dissolved and removed byreduction reaction. Such a process of removing the passive film (areverse electrolytic process) is executed on the stainless steel platein advance, so that the plating process is executed on the stainlesssteel plate and the conductor layer at the same time.

SUMMARY

In the plating method of JP 2014-210959 A, since the reverseelectrolytic process is executed on a member to be plated, the number ofsteps in the process increases, and the number of components of theplating apparatus increases. As a result, the cost required for theplating process increases.

An object of the present invention is to provide a plating method and amethod of manufacturing a printed circuit board that enable reduction ofa cost required for a plating process.

Generally, in a case in which the plating process is executed onstainless steel, an electrolytic solution (a woods bath) includingnickel chloride as a main component is used to remove a passive film ona surface. However, because a woods bath is highly corrosive, stainlesssteel may be damaged. Therefore, J P 2014-210595 A suggests that anelectrolytic solution including a highly corrosive component such aschlorine is not to be used.

It has been considered that, in a case in which a woods bath is used fora plating process for copper or a copper alloy (hereinafter simplyreferred to as copper), copper is more damaged than stainless steel.Further, since a passive film is hardly formed on the surface of copper,it is not necessary to use a woods bath in a plating process. Therefore,in a case in which a plating process is executed on copper, anelectrolytic solution (a watts bath) including nickel sulfate as a maincomponent has been used conventionally.

Also in the plating method of JP 2014-210959 A, an electrolytic solutionincluding nickel sulfate as a main component is used for a platingprocess for a stainless steel plate and copper. However, in the platingmethod of JP 2014-210595 A, it is required to execute a reverseelectrolytic process on the stainless steel plate in advance in order toremove a passive film on the surface of the stainless steel plate.

As a result of having repeated experiments and studies using variouselectrolytic solutions without conventional technical bias, theinventors of the present invention have found that stainless steel andcopper are not significantly damaged even in a case in which a woodsbath is used as an electrolytic solution. The inventors of the presentapplication have conceived the following configuration based on thisfinding.

(1) A plating method according to one aspect of the present inventionincludes preparing a laminate made of stainless steel, and copper or acopper alloy, and forming plating underlayers made of nickel on a firstplated portion provided at the stainless steel and a second platedportion provided at the copper or the copper alloy at a same time usinga hydrochloric acid electrolytic solution.

With this plating method, it is possible to form a plating underlayermade of nickel on the first plated portion made of stainless steel andthe second plated portion made of copper or a copper alloy at the sametime by using a hydrochloric acid electrolytic solution. In this case,an increase in number of steps required for the plating process isprevented. Therefore, the cost required for the plating process can bereduced.

(2) The forming plating underlayers may include forming platingunderlayers on the first plated portion and the second plated portionunder a same plating condition. In this case, the plating process can beexecuted on the first plated portion and the second plated portion inthe same plating tank. Therefore, the cost required for the platingprocess can be reduced more sufficiently.

(3) The plating condition may include a current density or a voltage.This more sufficiently facilitates formation of the plating underlayerson the first plated portion and the second plated portion at the sametime.

(4) The forming plating underlayers may include applying a voltage toeach of the first plated portion and the second plated portion using acommon electrode. In this case, an increase in number of componentsrequired for the plating process is prevented. Therefore, the costrequired for the plating process can be reduced more sufficiently.

(5) A concentration of hydrochloric acid in an electrolytic solution maybe not less than 60 ml/L. In this case, the adhesion between the firstplated portion and the second plated portion, and nickel is improved.This more sufficiently facilitates formation of the plating underlayerson the first plated portion and the second plated portion at the sametime.

(6) The plating method may further include forming plating underlayersmade of nickel on plating underlayers formed on the first plated portionand the second plated portion. In this case, plating underlayers havinga sufficiently large thickness can be formed on the first plated portionand the second plated portion.

(7) The plating method may further include forming plating layers madeof gold (Au) on plating underlayers formed on the first plated portionand the second plated portion. In this case, corrosion resistance of thesurface of the first plated portion and the second plated portion can beimproved, and wettability of a solder can be improved.

(8) The laminate may be a printed circuit board in which the stainlesssteel and a conductor layer made of copper or a copper alloy arelaminated, the first plate portion may be a first terminal portionprovided at the stainless steel, and the second plated portion may be asecond terminal portion provided at the conductor layer. In this case,in the printed circuit board, the plating underlayers made of nickel canbe formed on the first terminal portion made of stainless steel and thesecond terminal portion made of copper or a copper alloy at the sametime.

(9) A method of manufacturing a printed circuit board according toanother aspect of the present invention includes preparing a laminateincluding stainless steel and a conductor layer made of copper or acopper alloy, forming a first connection terminal and a secondconnection terminal at the laminate at a same time, forming the firstconnection terminal includes forming a plating underlayer made of nickelon a first terminal portion provided at the stainless steel using ahydrochloric acid electrolytic solution, and forming the secondconnection terminal includes forming a plating underlayer made of nickelon a second terminal portion provided at the conductor layer using ahydrochloric acid electrolytic solution.

With this method of manufacturing the printed circuit board, because ahydrochloric acid electrolytic solution is used, plating underlayersmade of nickel are formed on the first terminal portion made ofstainless steel and the second terminal portion made of copper or acopper alloy at the same time. Thus, the first connection terminal andthe second connection terminal are formed at the same time. In thiscase, an increase in number of steps required for manufacturing of theprinted circuit board is prevented. Therefore, the cost required formanufacturing of the printed circuit board can be reduced.

(10) The forming a first connection terminal and a second connectionterminal may include forming the first connection terminal and thesecond connection terminal under a same plating condition. In this case,the plating process can be executed on the first terminal portion andthe second terminal portion in the same plating tank. Therefore, thecost required for manufacturing of the printed circuit board can bereduced.

(11) The plating condition may include a current density or a voltage.In this case, formation of the plating underlayers on the first terminalportion and the second terminal portion at the same time is facilitatedmore sufficiently.

(12) The forming a first connection terminal and a second connectionterminal may include applying a voltage to each of the first terminalportion and the second terminal portion using a common electrode. Inthis case, an increase in number of components required formanufacturing of the printed circuit board is prevented. Therefore, thecost required for manufacturing of the printed circuit board can bereduced.

(13) A concentration of hydrochloric acid in an electrolytic solutionmay be not less than 60 ml/L. In this case, the adhesion between thefirst plated portion and the second plated portion, and nickel isimproved. This more sufficiently facilitates formation of the platingunderlayers on the first plated portion and the second plated portion atthe same time.

(14) The forming the first connection terminal further may includeforming a plating underlayer made of nickel on a plating underlayerformed on the first terminal portion, and the forming the secondconnection terminal may further include forming a plating underlayermade of nickel on a plating underlayer formed on the second terminalportion. In this case, plating underlayers having a sufficiently largethickness can be formed on the first terminal portion and the secondterminal portion.

(15) The forming the first connection terminal may include forming aplating layer made of gold (Au) on a plating underlayer formed on thefirst terminal portion, and the forming the second connection terminalmay further include forming a plating layer made of gold (Au) on aplating underlayer formed on the second terminal portion. In this case,corrosion resistance of the surface of the first connection terminal andthe second connection terminal can be improved, and wettability of asolder can be improved.

Other features, elements, characteristics, and advantages of the presentdisclosure will become more apparent from the following description ofpreferred embodiments of the present disclosure with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram showing the configuration of a platingapparatus that is used when a plating method according to an embodimentof the present invention is performed;

FIG. 2 shows SEM photographs of the appearance of a laminate in aninventive example;

FIG. 3 shows SEM photographs of the appearance of the laminate in acomparative example;

FIG. 4 is a plan view of a suspension board;

FIG. 5 is a cross sectional view of the suspension board of FIG. 4 takenalong the line A-A;

FIG. 6 is an enlarged plan view of a tongue as viewed from one side;

FIG. 7 is an enlarged plan view of the tongue as viewed from the otherside;

FIG. 8 is a cross sectional view of the tongue of each of FIGS. 6 and 7taken along the line B-B;

FIG. 9 is a cross sectional view of the tongue of each of FIGS. 6 and 7taken along the line C-C;

FIG. 10 is a block diagram showing the configuration of a plating systemthat is used in a method of manufacturing a suspension board;

FIG. 11 is a cross sectional view for explaining the step in the methodof the manufacturing the suspension board;

FIG. 12 is a cross sectional view for explaining the step in the methodof the manufacturing the suspension board;

FIG. 13 is a cross sectional view for explaining the step in the methodof the manufacturing the suspension board;

FIG. 14 is a cross sectional view for explaining the step in the methodof the manufacturing the suspension board; and

FIG. 15 is a cross sectional view for explaining the step in the methodof the manufacturing the suspension board.

DETAILED DESCRIPTION [1] Plating Apparatus

(1) Configuration of Plating Apparatus

A plating method and a method of manufacturing a printed circuit boardaccording to embodiments of the present invention will be describedbelow with reference to the drawings. FIG. 1 is a schematic diagramshowing the configuration of a plating apparatus that is used when aplating method according to an embodiment of the present invention isperformed. As shown in FIG. 1 , the plating apparatus 100 includes aplating tank 110, a pair of transport rollers 120, a roller driver 130,a power feed roller 140, an electrode 150, a rectifier 160 and acontroller 170. The roller driver 130 and the rectifier 160 arecontrolled by the controller 170.

In the present embodiment, a member to be plated is a laminate 1 havingan elongated shape. The laminate 1 includes a stainless steel plate 2,an insulating layer 3, and a conductor layer 4 made of copper or acopper alloy. The insulating layer 3 includes polyimide, for example.The stainless steel plate 2 is formed on one surface of the insulatinglayer 3. The conductor layer 4 is formed on the other surface of theinsulating layer 3.

On the surface of each of the stainless steel plate 2 and the conductorlayer 4, a plurality of portions on which a plating underlayer is to beformed by the plating apparatus 100 are provided. Hereinafter, a portionof the laminate 1 on which a plating underlayer is to be formed isreferred to as a plated portion. In particular, a portion of the surfaceof the stainless steel plate 2 on which a plating underlayer is to beformed is referred to as a first plated portion, and a portion of thesurface of the conductor layer 4 on which a plating underlayer is to beformed is referred to as a second plated portion.

An electrolytic solution is stored in the plating tank 110. Theelectrolytic solution includes nickel chloride hexahydrate (hereinaftersimply referred to as nickel chloride) and hydrochloric acid as maincomponents. The concentration of nickel chloride in the electrolyticsolution is preferably not lower than 100 g/L and lower than 360 g/L.When the concentration of nickel chloride is not lower than 100 g/L,current efficiency is improved. Further, when the concentration ofnickel chloride is lower than 360 g/L, the thickness of a platingunderlayer is prevented from being non-uniform. Further, an increase incost is suppressed.

The concentration of hydrochloric acid in the electrolytic solution ispreferably not lower than 60 ml/L and lower than 280 ml/L. When theconcentration of hydrochloric acid is not lower than 60 ml/L, currentefficiency is improved. Further, the adhesion between each of the firstand second plated portions, and nickel is improved. This moresufficiently facilitates formation of the plating underlayers on thefirst plated portion and the second plated portion at the same time.When the concentration of hydrochloric acid is lower than 280 ml/L,degradation of deposition efficiency of nickel can be prevented.

The temperature of the electrolytic solution is not lower than 15° C.and lower than 40° C., for example, and is preferably 25° C. When thetemperature of the electrolytic solution is lower than 40° C., corrosionof metal due to generation of a hydrogen chloride gas can be prevented.

The laminate 1 is held by the pair of transport rollers 120. When thepair of transport rollers 120 are rotationally driven by the rollerdriver 130, the laminate 1 is transported. The plating tank 110 isprovided with a carry-in port 101 and a carry-out port 102. The laminate1 is carried into the plating tank 110 through the carry-in port 101 andcarried out from the plating tank 110 through the carry-out port 102. Inthis case, in the plating tank 110, the laminate 1 is transported in thedirection of the arrow MD (hereinafter referred to as a transportdirection) in the electrolytic solution. Thus, the plating apparatus 100executes a plating process on the laminate 1 using a roll-to-rollmethod.

When the speed at which the laminate 1 is transported is controlled, aplating period of time is adjusted. While the plating period of time isnot less than 10 seconds and not more than 300 seconds, for example, theembodiment is not limited to this. The plating period of time issuitably set according to the thickness of a plating underlayer to beformed. The upper limit of the plating period of time is preferably setsuch that the first and second plated portions are not damaged.

The power feed roller 140 is arranged outside of the plating tank 110.The power feed roller 140 may be arranged at a position farther upstreamthan the carry-in port 101 or may be arranged at a position fartherdownstream than the carry-out port 102. Further, the power feed roller140 comes into contact with a portion of the stainless steel plate 2 orthe conductor layer 4 of the laminate 1. The power feed roller 140 isprovided to be rotatable so as not to cause friction between the powerfeed roller 140 and the laminate 1. The power feed roller 140 may berotationally driven by a motor or the like such that a force is appliedfrom the power feed roller 140 to the laminate 1 in the transportdirection.

The electrode 150 is arranged in the plating tank 110 so as to beopposite to the stainless steel plate 2 or the conductor layer 4 of thelaminate 1. As a material of the electrode 150, stainless steel, nickelor platinum is used, for example. The power feed roller 140 is connectedto a positive electrode of the rectifier 160, and the electrode 150 isconnected to a negative electrode of the rectifier 160. The rectifier160 applies a voltage between the laminate 1 that comes into contactwith the power feed roller 140 and the electrode 150. In this case, thelaminate 1 serves as a cathode, and the electrode 150 serves as ananode.

The current density in the electrolytic solution caused by the rectifier160 (the current density between the electrode 150 and the laminate 1)is preferably not lower than 2 A/dm² and lower than 50 A/dm². When thecurrent density in the electrolytic solution caused by the rectifier 160is not less than 2 A/dm², the adhesion between a plated portion and aplating underlayer is improved. Further, when the current density in theelectrolytic solution caused by the rectifier 160 is lower than 50A/dm², a voltage applied between the laminate 1 having high electricresistance and the electrode 150 is prevented from being excessivelyhigh.

(2) Plating Method

A method of plating the laminate 1 using the plating apparatus 100 ofFIG. 1 will be described. The below-mentioned operation of the platingapparatus 100 is realized when the roller driver 130 and the rectifier160 are controlled by the controller 170.

The laminate 1 is carried into the plating tank 110 through the carry-inport 101 by the transport roller 120 and transported in the transportdirection. When the first plated portion in the stainless steel plate 2and the second plated portion in the conductor layer 4 are carried intothe plating tank 110, a voltage is applied between the first platedportion and the electrode 150 by the rectifier 160, and a voltage isapplied between the second plated portion and the electrode 150 by therectifier 160.

Thus, nickel is deposited on the first and second plated portions at thesame time. As a result, plating underlayers made of nickel are formed onthe first and second plated portions. Hereinafter, such a process offorming plating underlayers is referred to as an electrolytic platingprocess. The thickness of a plating underlayer is not less than 0.01 μmand not more than 3.0 μm, for example.

Similarly, the electrolytic plating process is executed on a portion tobe plated each time an unprocessed plated portion in the laminate 1 istransported into the plating tank 110. In this manner, after a platingunderlayer is formed on a plated portion, a plating underlayer made ofnickel may further be formed by electrolytic plating on the platingunderlayer in another plating tank (not shown). In this case, a platingunderlayer having a sufficiently large thickness can be formed on theplated portion.

Alternatively, after a plating underlayer is formed on a plated portion,a plating layer (hereinafter referred to as a main plating layer) madeof gold (Au) may be formed by electrolytic plating on the platingunderlayer in another plating tank (not shown). In this case, corrosionresistance of the surface of the plated portion can be improved, andwettability of a solder can be improved. The thickness of the mainplating layer is not less than 0.1 μm and not more than 5.0 μm, forexample.

(3) Effects

With the plating method according to the present embodiment, it ispossible to form plating underlayers made of nickel on the first platedportion made of stainless steel and the second plated portion made ofcopper or a copper alloy at the same time by using a hydrochloric acidelectrolytic solution. In this case, an increase in number of stepsrequired for the plating process is prevented. Therefore, the costrequired for the plating process can be reduced.

The plating underlayers are formed on the first plated portion and thesecond plated portion under the same plating condition. Specifically,the plating underlayers are formed on the first plated portion and thesecond plated portion at the same current density (that is a voltage).In this case, the plating process can be executed on the first platedportion and the second plated portion in the same plating tank.Therefore, the cost required for the plating process can be reduced moresufficiently. Further, this more sufficiently facilitates formation ofthe plating underlayers on the first and second plated portions at thesame time.

The plating underlayers are formed by application of a voltage to eachof the first plated portion and the second plated portion with use ofthe common electrode 150. In this case, an increase in number ofcomponents required for the plating process is prevented. Therefore, thecost required for the plating process can be reduced more sufficiently.

[2] Inventive Examples

In each of the inventive examples 1 to 4 and the comparative examples 1to 3, described below, a plating underlayer was formed by the platingapparatus 100 on each of the stainless steel plate 2 and the conductorlayer 4 of the laminate 1 under various conditions. The stainless steelplate 2 is made of SUS304.

In the inventive example 1, a copper-foil CF-T49A-DS-HD2-18(manufactured by FUKUDA METAL FOIL & POWDER Co., LTD.) was used as theconductor layer 4. As a pre-process, the surface of the laminate 1 wasdegreased with a degreasing liquid, and then soft etching was performedon the surface of the conductor layer 4 of the laminate 1. Further, thelaminate 1 on which the soft etching has been performed was sufficientlycleaned with acid. After the pre-process, the electrolytic platingprocess was executed. In the electrolytic plating process, a woods bathwas used as an electrolytic solution. The current density in theelectrolytic solution was 2 A/dm², and the temperature of theelectrolytic solution was 25° C. The concentration of nickel chloride inthe electrolytic solution was 240 g/L, and the concentration ofhydrochloric acid was 120 ml/L. A plating period of time was 60 seconds.

In an inventive example 2, the pre-process and the electrolytic platingprocess were executed similarly to the inventive example 1 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 15 A/dm², and the temperature ofthe electrolytic solution was 30° C. The concentration of nickelchloride in the electrolytic solution was 280 g/L, and the concentrationof hydrochloric acid was 140 ml/L. A plating period of time was 30seconds.

In an inventive example 3, the pre-process and the electrolytic platingprocess were executed similarly to the inventive example 2 except forthe following points. In the electrolytic plating process, the currentdensity in the electrolytic solution was 30 A/dm², and the temperatureof the electrolytic solution was 20° C. The concentration of nickelchloride in the electrolytic solution was 200 g/L, and the concentrationof hydrochloric acid was 100 ml/L.

In an inventive example 4, the pre-process and the electrolytic platingprocess were executed similarly to the inventive example 1 except that acopper alloy foil HS1200 (manufactured by JX Nippon Mining & MetalsCorporation) was used as the conductor layer 4.

In a comparative example 1, a copper foil CF-T49A-DS-HD2-18(manufactured by FUKUDA METAL FOIL & POWDER Co., LTD.) was used as theconductor layer 4. After the pre-process was executed similarly to theinventive example 1, the electrolytic plating process was executed. Inthe electrolytic plating process, a watts bath was used as anelectrolytic solution. The current density in the electrolytic solutionwas 2 A/dm², and the temperature of the electrolytic solution was 55° C.The concentration of nickel chloride in the electrolytic solution was 64g/L, the concentration of nickel sulfate hexahydrate (hereinafter simplyreferred to as nickel sulfate) was 260 g/L, and the concentration ofboric acid was 33 ml/L. A plating period of time was 60 seconds.

In a comparative example 2, the pre-process and the electrolytic platingprocess were executed similarly to the comparative example 1 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 15 A/dm², and a plating periodof time was 30 seconds.

In a comparative example 3, the pre-process and the electrolytic platingprocess were executed similarly to the comparative example 1 except thata copper alloy foil HS1200 (manufactured by JX Nippon Mining & MetalsCorporation) was used as the conductor layer 4.

The adhesion of the plating underlayers formed in the inventive examples1 to 4 and the comparative Examples 1 to 3 was evaluated by a cross-cuttest. Table 1 shows the plating conditions and the evaluation results inregard to the adhesion of the plating underlayers in the inventiveexamples 1 to 4 and the comparative examples 1 to 3.

TABLE 1 INVENTIVE INVENTIVE INVENTIVE INVENTIVE COMPARATIVE COMPARATIVECOMPARATIVE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE 1 23 4 1 2 3 ELECTROLYTIC WOODS WOODS WOODS WOODS WATTS WATTS WATTSSOLUTION BATH BATH BATH BATH BATH BATH BATH CONDUCTOR COPPER COPPERCOPPER COPPER COPPER COPPER COPPER LAYER ALLOY ALLOY CURRENT 2 15 30 2 215 2 DENSITY [A/dm²] TEMPERATURE 25 30 20 25 55 55 55 OF ELECTROLYTICSOLUTION [° C.] CONCENTRATION 240 280 200 240 64 64 64 OF NICKELCHLORIDE[g/L] CONCENTRATION 120 140 100 120 OF HYDROCHLORIC ACID[m/L]CONCENTRATION 260 260 260 OF NICKEL SULFATE[g/L] CONCENTRATION 33 33 33OF BORIC ACID [g/L] PLATING PERIOD 60 30 30 80 80 80 80 OF TIME[seconds] EVALUATION GOOD GOOD GOOD GOOD NOT GOOD NOT GOOD NOT GOOD

As shown in Table 1, as a result of the cross-cut test, in each of theinventive examples 1 to 4, the plating underlayer was not stripped awayfrom the stainless steel plate 2 or the conductor layer 4. On the otherhand, in each of the comparative examples 1 to 3, although the platingunderlayer was not stripped away from the conductor layer 4, the platingunderlayer was stripped away from the stainless steel plate 2.

Further, the adhesion of a plating underlayer was evaluated in regard toappearance of a laminate 1. FIG. 2 shows SEM (scanning electronmicroscope) photographs of the appearance of the laminate 1 in theinventive example. The left SEM photograph of FIG. 2 shows the crosssection of the boundary between the conductor layer 4 and the platingunderlayer in the inventive example 2. The right SEM photograph of FIG.2 shows the cross section of the boundary between the stainless steelplate 2 and the plating underlayer in the inventive example 2.

As shown in FIG. 2 , in a case in which a woods bath was used as anelectrolytic solution, voids were not generated in the boundary betweenthe conductor layer 4 and the plating underlayer or the boundary betweenthe stainless steel plate 2 and the plating underlayer. Thus, it wasconfirmed that, in a case in which a woods bath was used as anelectrolytic solution, adhesion of a plating underlayer was improved.

FIG. 3 shows SEM photographs of the appearance of the laminate 1 in thecomparative example. The left SEM photograph in FIG. 3 shows the crosssection of the boundary between the conductor layer 4 and the platingunderlayer in the comparative example 1. The right SEM photograph inFIG. 3 shows the cross section of the boundary between the stainlesssteel plate 2 and the plating underlayer in the comparative example 1.When the plating underlayer of FIG. 3 is formed, the current density inthe electrolytic solution was 4 A/dm², and the plating period of timewas 150 seconds.

As shown in FIG. 3 , in a case in which a watts bath was used as anelectrolytic solution, voids were not generated in the boundary betweenthe conductor layer 4 and the plating underlayer. However, voids weregenerated in the boundary between the stainless steel plate 2 and theplating underlayer. Thus, it was confirmed that, in a case in which awatts bath was used as an electrolytic solution, adhesion of a platingunderlayer was not good.

[3] Reference Example

(1) Stainless Steel Plate

In the following reference examples 1 to 5, a plating underlayer wasformed on a stainless steel plate under various conditions by theplating apparatus 100, and evaluation was conducted. The stainless-steelplate is made of SUS304.

In the reference example 1, after the pre-process was executed similarlyto the inventive example 1, the electrolytic plating process wasexecuted. In the electrolytic plating process, a woods bath was used asan electrolytic solution. The current density in the electrolyticsolution was 2 A/dm², and the temperature of the electrolytic solutionwas 25° C. The concentration of nickel chloride in the electrolyticsolution was 240 g/L, and the concentration of hydrochloric acid was 120ml/L. A plating period of time was 60 seconds.

In the reference example 2, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 1 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 15 A/dm², and a plating periodof time was 30 seconds.

In the reference example 3, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 2 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 30 A/dm².

In the reference example 4, after the pre-process was executed similarlyto the reference example 1, the electrolytic plating process wasexecuted. In the electrolytic plating process, a watts bath was used asan electrolytic solution. The current density in the electrolyticsolution was 2 A/dm², and the temperature of the electrolytic solutionwas 55° C. The concentration of nickel chloride in the electrolyticsolution was 64 g/L, the concentration of nickel sulfate was 260 g/L,and the concentration of boric acid was 33 ml/L. A plating period oftime was 60 seconds.

In the reference example 5, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 4 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 15 A/dm², and a plating periodof time was 30 seconds.

The adhesion of the plating underlayers formed in the reference examples1 to 5 was evaluated by a cross-cut test. Table 2 shows the platingconditions and the evaluation results in regard to adhesion of theplating underlayers in the reference examples 1 to 5.

TABLE 2 REFERENCE REFERENCE REFERENCE REFERENCE REFERENCE EXAMPLE 1EXAMPLE 1 EXAMPLE 3 EXAMPLE 4 EXAMPLE 5 ELECTROLYTIC WOODS WOODS WOODSWATTS WATTS SOLUTION BATH BATH BATH BATH BATH CURRENT 2 15 30 2 15DENSITY [A/dm²] TEMPERATURE 25 25 25 55 55 OF ELECTROLYTIC SOLUTION [°C.] CONCENTRATION 240 240 240 64 64 OF NICKEL CHLORIDE [g/L]CONCENTRATION 120 120 120 OF HYDROCHLORIC ACID [ml/L] CONCENTRATION 280230 OF NICKEL SULFATE [g/L] CONCENTRATION 33 OF BORIC ACID [g/L] PLATINGPERIOD 60 30 30 60 30 OF TIME [seconds] EVALUATION GOOD GOOD GOOD NOTGOOD NOT GOOD

As shown in Table 2, as a result of the cross-cut test, in each of thereference examples 1 to 3, the plating underlayer was not stripped awayfrom the stainless steel plate. On the other hand, in each of thereference examples 4 and 5, the plating underlayer was stripped awayfrom the stainless steel plate. As a result, it was confirmed that, in acase in which a woods bath was used as an electrolytic solution,adhesion of a plating underlayer was good.

On the other hand, it was confirmed that, in a case in which a wattsbath was used as an electrolytic solution, adhesion of a platingunderlayer was not good. It is considered that, this is because apassive film formed on the surface of a stainless steel plate cannot beremoved in a case in which a watts bath is used as an electrolyticsolution.

(2) Conductor Layer

In each of the following reference examples 6 to 12, a platingunderlayer was formed on a conductor layer under various conditions bythe plating apparatus 100, and evaluation was conducted.

In the comparative example 6, a copper-foil CF-T49A-DS-HD2-18(manufactured by FUKUDA METAL FOIL & POWDER Co., LTD.) was used as aconductor layer. After the pre-process was executed similarly to theinventive example 1, the electrolytic plating process was executed. Inthe electrolytic plating process, a woods bath was used as anelectrolytic solution. The current density in the electrolytic solutionwas 2 A/dm², and the temperature of the electrolytic solution was 25° C.The concentration of nickel chloride in the electrolytic solution was240 g/L, and the concentration of hydrochloric acid was 120 ml/L. Aplating period of time was 60 seconds.

In the reference example 7, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 6 except forthe following points. In the electrolytic plating process, theelectrolytic plating process was executed similarly to theabove-mentioned reference example 6 except that the current density inthe electrolytic solution was 15 A/dm², and a plating period of time was30 seconds.

In the reference example 8, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 7 except forthe following points. In the electrolytic plating process, the currentdensity in an electrolytic solution was 30 A/dm².

In the reference example 9, the pre-process and the electrolytic platingprocess were executed similarly to the reference example 6 except that acopper alloy foil HS1200 (manufactured by JX Nippon Mining & MetalsCorporation) was used as a conductor layer.

In the comparative example 10, a copper foil CF-T49A-DS-HD2-18(manufactured by FUKUDA METAL FOIL & POWDER Co., LTD.) was used as aconductor layer. After the pre-process was executed similarly to thereference example 1, the electrolytic plating process was executed. Inthe electrolytic plating process, a watts bath was used as anelectrolytic solution. The current density in the electrolytic solutionwas 2 A/dm², and the temperature of the electrolytic solution was 55° C.The concentration of nickel chloride in the electrolytic solution was 64g/L, the concentration of nickel sulfate was 260 g/L, and theconcentration of boric acid was 33 ml/L. A plating period of time was 60seconds.

In the reference example 11, the pre-process and the electrolyticplating process were executed similarly to the reference example 10except for the following points. In the electrolytic plating process,the current density in the electrolytic solution was 4 A/dm², and aplating period of time was 30 seconds.

In the reference example 12, the pre-process and the electrolyticplating process were executed similarly to the reference example 10except that a copper alloy foil HS1200 (manufactured by JX Nippon Mining& Metals Corporation) was used as a conductor layer.

The adhesion of the plating underlayers formed in the reference examples6 to 12 was evaluated by a cross-cut test. Table 3 shows the platingconditions and the evaluation results in regard to adhesion of theplating underlayers in the reference examples 6 to 12.

TABLE 3 REFERENCE REFERENCE REFERENCE REFERENCE REFERENCE REFERENCEREFERENCE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE 6 7 89 10 11 12 ELECTROLYTIC WOODS WOODS WOODS WOODS WATTS WATTS WATTSSOLUTION BATH BATH BATH BATH BATH BATH BATH CONDUCTOR COPPER COPPERCOPPER COPPER COPPER COPPER COPPER LAYER ALLOY ALLOY CURRENT 2 15 30 2 24 2 DENSITY [A/dm²] TEMPERATURE 25 25 25 25 55 55 55 OF ELECTROLYTICSOLUTION [° C.] CONCENTRATION 240 240 240 240 64 64 64 OF NICKELCHLORIDE[g/L] CONCENTRATION 120 120 120 120 OF HYDROCHLORIC ACID[m/L]CONCENTRATION 260 260 260 OF NICKEL SULFATE[g/L] CONCENTRATION 33 33 33OF BORIC ACID [g/L] PLATING PERIOD 60 30 30 60 60 30 60 OF TIME[seconds] EVALUATION GOOD GOOD GOOD GOOD GOOD GOOD GOOD

As shown in Table 3, as a result of the cross-cut test, in each of thereference examples 6 to 12, the plating underlayer was not stripped awayfrom the conductor layer. As a result, it was confirmed that, in a casein which either of a woods bath and a watts bath was used as anelectrolytic solution, adhesion of a plating underlayer was good. It isconsidered that, this is because a passive film is hardly formed on thesurface of a conductor layer.

[4] Method of Manufacturing Printed Circuit Board

(1) Configuration of Suspension Board

A method of manufacturing a printed circuit board according toembodiments of the present invention will be described. A printedcircuit board in the following embodiments is a suspension board with acircuit (hereinafter abbreviated as suspension board) used for anactuator of a hard disc drive device.

FIG. 4 is a plan view of a suspension board. FIG. 5 is a cross sectionalview of the suspension board 1A of FIG. 4 taken along the line A-A. Asshown in FIGS. 4 and 5 , the suspension board 1A includes an elongatedsupport substrate 10. The support substrate 10 is made of stainlesssteel.

A base insulating layer 11 made of polyimide, for example, is formed onthe support substrate 10. Write wiring traces W1, W2, read wiring tracesR1, R2 and heat-assisted wiring traces H1, H2 are formed on the baseinsulating layer 11. The write wiring traces W1, W2, the read wiringtraces R1, R2 and the heat-assisted wiring traces H1, H2 are made ofcopper (Cu) or a copper alloy.

The write wiring traces W1, W2 and the heat-assisted wiring trace H1 areformed in a region extending along one side of the support substrate 10.The heat-assisted wiring trace H1 is arranged outwardly of the writewiring traces W1, W2. The read wiring traces R1, R2 and theheat-assisted wiring trace H2 are formed in a region extending along theother side of the support substrate 10. The heat-assisted wiring traceH2 is arranged outwardly of the read wiring traces R1, R2.

At one end of the support substrate 10, a magnetic head supportingportion (hereinafter referred to as a tongue) 50 is provided byformation of a U-shaped opening 40. One end of each of the write wiringtraces W1, W2, the read wiring traces R1, R2 and the heat-assistedwiring traces H1, H2 extends on the tongue 50. On the tongue 50, aconnection terminal 21 is provided at one end of the write wiring traceW1, and a connection terminal 22 is provided at one end of the writewiring trace W2. Further, a connection terminal 23 is provided at oneend of the read wiring trace R1, and a connection terminal 24 isprovided at one end of the read wiring trace R2.

Further, on the tongue 50, a land portion L1 is provided at one end ofthe heat-assisted wiring trace H1, and a land portion L2 is provided atone end of the heat-assisted wiring trace H2. As described below, theland portions L1, L2 are connected to the connection terminals 25, 26(FIG. 7 ), respectively.

On the other end of the support substrate 10, a connection terminal 31is provided at the other end of the write wiring trace W1, and aconnection terminal 32 is provided at the other end of the write wiringtrace W2. Further, a connection terminal 33 is provided at the other endof the read wiring trace R1, and a connection terminal 34 is provided atthe other end of the read wiring trace R2. Further, a connectionterminal 35 is provided at the other end of the heat-assisted wiringtrace H1, and a connection terminal 36 is provided at the other end ofthe heat-assisted wiring trace H2.

A cover insulating layer 12 made of polyimide, for example, is formed onthe base insulating layer 11 to cover portions of the write wiringtraces W1, W2, the read wiring traces R1, R2 and the heat-assistedwiring traces H1, H2 except for the connection terminals 21 to 24, 31 to36. Under the cover insulating layer 12, a metal film made of nickel,for example, may be formed so as to cover each of the write wiringtraces W1, W2, the read wiring traces R1, R2 and the heat-assistedwiring traces H1, H2.

(2) Tongue

Details of the tongue 50 will be described. FIG. 6 is an enlarged planview of the tongue 50 as viewed from one side (the same side as FIG. 4). FIG. 7 is an enlarged plan view of the tongue 50 as viewed from theother side (the opposite side to FIG. 4 ). FIG. 8 is a cross sectionalview of the tongue 50 of each of FIGS. 6 and 7 taken along the line B-B.FIG. 9 is a cross sectional view of the tongue 50 of each of FIGS. 6 and7 taken along the line C-C.

As shown in FIG. 6 , the connection terminals 21 to 24 of the writewiring traces W1, W2 and the read wiring traces R1, R2 are not coveredby the cover insulating layer 12. On the other hand, the land portionsL1, L2 of the heat-assisted wiring traces H1, H2 are covered by thecover insulating layer 12. A rectangular opening OP is formed in thebase insulating layer 11. The connection terminals 21 to 24 are arrangedto extend along one side of the opening OP.

As shown in FIG. 7 , an opening 10 a is formed in the support substrate10. The opening OP of the base insulating layer 11 overlaps with part ofthe opening 10 a of the support substrate 10. In the opening 10 a, theconnection terminals 25, 26 are provided on the lower surface of thebase insulating layer 11. One end of the connection terminal 25 overlapswith the land portion L1 of FIG. 6 , and one end of the connectionterminal 26 overlaps with the land portion L2 of FIG. 6 . The other endof each of the connection terminals 25, 26 is arranged so as to beextend along the above-mentioned one side of the opening OP of the baseinsulating layer 11.

In the following description, the one end of the write wiring trace W1is referred to as a terminal portion 21 a, and the one end of the writewiring trace W2 is referred to as a terminal portion 22 a. Similarly,the one end of the read wiring trace R1 is referred to as a terminalportion 23 a, and the one end of the read wiring trace R2 is referred toas a terminal portion 24 a. Further, portions of the support substrate10 formed in the opening 10 a of the support substrate 10 are referredto as terminal portions 25 a, 26 a. The terminal portions 25 a, 26 a areseparated from the rest of the support substrate 10. As shown in FIG. 8, cover layers 60 made of a plurality of plating layers are formed so asto cover the side surfaces and the upper surface of each of the terminalportions 21 a to 24 a. Thus, the connection terminals 21 to 24 areformed.

As shown in FIG. 9 , tapered holes 11 a, 11 b are respectively formed inportions of the base insulating layer 11 on the one end of the terminalportion 25 a and the one end of the terminal portion 26 a. The landportion L1 is provided so as to come into contact with the upper surfaceof the base insulating layer 11, the inner peripheral surface of thehole 11 a and the upper surface of the terminal portion 25 a. The landportion L2 is provided so as to come into contact with the upper surfaceof the base insulating layer 11, the inner peripheral surface of thehole 11 b and the upper surface of the terminal portion 26 a. A coverlayer 60 made of a plurality of plating layers is formed so as to coverthe side surfaces and the lower surface of each of the terminal portions25 a, 26 a. Thus, the connection terminals 25, 26 are formed.

A slider (not shown) including a magnetic head is attached to the uppersurface of the tongue 50. Connection terminals of the slider areelectrically connected to the connection terminals 21 to 24 of the writewiring traces W1, W2 and the read wiring traces R1, R2. A heat-assisteddevice such as a laser diode is attached to the lower surface of theslider so as to project from the lower surface of the tongue 50 throughthe opening OP of the base insulating layer 11 and the opening 10 a ofthe support substrate 10. Connection terminals of the heat-assisteddevice are electrically connected to the connection terminals 25, 26.When information is written into a magnetic disc by the magnetic head,the magnetic disc is heated by the heat-assisted device. Thus, densityof the information to be written into the magnetic disc can be improved.

(3) Plating System

FIG. 10 is a block diagram showing the configuration of a plating systemused in a method of manufacturing the suspension board 1A. As shown inFIG. 10 , the plating system 200 includes the plating apparatus 100 ofFIG. 1 and includes a pre-processing device 210, plating apparatuses220, 230, 240, cleaning devices 250, 260, 270, 280 and a drying device290. The pre-processing device 210 is provided at the most upstreamposition of the plating system 200 and executes a pre-process on thesuspension board 1A. The pre-process includes degreasing and cleaningwith acid.

The plating apparatuses 100, 220, 230, 240 are provided in this orderfrom an upstream position to a downstream position. The platingapparatuses 220, 230, 240 basically have the configuration similar tothat of the plating apparatus 100 except that an electrolytic liquid isdifferent. The cover layer 60 of FIGS. 8 and 9 is constituted by platinglayers sequentially formed by the plating apparatuses 100, 220, 230,240.

The plating apparatus 100 executes an electrolytic plating process(hereinafter referred to as a strike plating process) using a relativelyhigh current for a short period of time on a plated portion of thesuspension board 1A on which the pre-process has been executed by thepre-processing device 210, thereby forming a thin plating underlayermade of nickel on the plated portion. The cleaning device 250 isprovided between the plating apparatus 100 and the plating apparatus 220and cleans the suspension board 1A on which the strike plating processhas been executed by the plating apparatus 100 with water.

The plating apparatus 220 executes an electrolytic plating process(hereinafter referred to as a soft plating process) using a relativelylow current on the plated portion of the suspension board 1A which hasbeen cleaned by the cleaning device 250. In this case, a platingunderlayer 62 of FIG. 13 , described below, having a sufficiently largethickness can be formed. The cleaning device 260 is provided between theplating apparatus 220 and the plating apparatus 230 and cleans thesuspension board 1A on which the soft plating process has been executedby the plating apparatus 220 with water.

The plating apparatus 230 executes the strike plating process for ashort period of time on the plated portion of the suspension board 1Athat has been cleaned by the cleaning device 260, thereby forming a thinmain plating layer made of gold (Au) on the thick plating underlayer.The cleaning device 270 is provided between the plating apparatus 230and the plating apparatus 240 and cleans the suspension board 1A onwhich the strike plating process has been executed by the platingapparatus 230 with water.

The plating apparatus 240 executes the soft plating process for a longperiod of time on the plated portion of the suspension board 1A that hasbeen cleaned by the cleaning device 270, thereby forming a thick mainplating layer made of gold (Au) on the thin main plating underlayer.Since the main plating layer is formed, corrosion resistance of thesurface of the plated portion can be improved, and wettability of asolder can be improved. The cleaning device 280 is provided at aposition farther downstream than the plating apparatus 240 and cleansthe suspension board 1A on which the soft plating process has beenexecuted by the plating apparatus 240 with water. The drying device 290is provided at the most downstream position of the plating system 200and dries the suspension board 1A that has been cleaned by the cleaningdevice 280.

(4) Method of Manufacturing Suspension Board

FIGS. 11 to 15 are cross sectional views for explaining the steps in themethod of the manufacturing the suspension board 1A. In the upper fieldsof FIGS. 11 to 15 , the steps of manufacturing the connection terminal21 of FIG. 8 are shown. In the lower fields of FIGS. 11 to 15 , thesteps of manufacturing the connection terminal 25 of FIG. 8 are shown.The method of manufacturing the suspension board 1A will be describedbelow with use of the plating system 200 of FIG. 10 and the crosssectional views for explaining the steps in FIGS. 11 to 15 .

First, as shown in FIG. 11 , the suspension board 1A is prepared as thelaminate 1. In the suspension board 1A, the support substrate 10 and theterminal portions 25 a, 26 a, which are a stainless-steel plate, areformed on the lower surface of the base insulating layer 11. Further,the write wiring traces W1, W2, the read wiring traces R1, R2 and theheat-assisted wiring traces H1, H2 that are conductor layers are formedon the upper surface of the base insulating layer 11. In FIGS. 11 to 15, the terminal portions 22 a to 24 a, 26 a, the write wiring traces W1,W2, the read wiring traces R1, R2, the heat-assisted wiring traces H1,H2 and the cover insulating layer 12 are not shown.

A plating resist layer (not shown) is formed on the surfaces of thestainless steel plate and the conductor layer excluding first and secondplated portions. In the present example, the terminal portions 25 a, 26a are the first plated portions. One end (terminal portions 21 a to 24a) and the other end of each of the write wiring traces W1, W2 and theread wiring traces R1, R2 are the second plated portions.

The steps of manufacturing the connection terminals 22 to 24, 31 to 36are similar to the steps of manufacturing the connection terminal 21.The steps of manufacturing the connection terminal 26 are similar to thesteps of manufacturing the connection terminal 25. Therefore, in thefollowing description, the connection terminals 22 to 24, 26, 31 to 36will not be mentioned.

In the pre-processing device 210, a pre-process is executed on thesuspension board 1A. Also in this case, as shown in FIG. 11 , a firmpassive film 5 formed on the surfaces of the support substrate 10 andthe terminal portion 25 a remains without being removed.

Next, as shown in FIG. 12 , the strike plating process is executed onthe plated portions of the suspension board 1A in the plating apparatus100. Thus, a plating underlayer 61 made of nickel is formed so as tocover the side surfaces and the upper surface of the terminal portion 21a. Further, a plating underlayer 61 made of nickel is formed so as tocover the side surfaces and the lower surface of the terminal portion 25a. In this step, the passive films 5 formed on the support substrate 10and the terminal portion 25 a are removed by an electrolytic solution.After the plating underlayers 61 are formed, the suspension board 1A iscleaned in the cleaning device 250.

Subsequently, as shown in FIG. 13 , the soft plating process is executedon the plated portions of the suspension board 1A in the platingapparatus 220. Thus, a plating underlayer 62 made of nickel is formed soas to cover the side surfaces and the upper surface of the platingunderlayer 61 of the terminal portion 21 a. Further, a platingunderlayer 62 made of nickel is formed so as to cover the side surfacesand the lower surface of the plating underlayer 61 of the terminalportion 25 a. The thickness of the plating underlayers 62 is larger thanthe thickness of the plating underlayers 61. The plating underlayers 62may be formed on the terminal portion 21 a and the terminal portion 25 aat the same time under the same plating condition. After the platingunderlayers 62 are formed, the suspension board 1A is cleaned in thecleaning device 260.

Thereafter, as shown in FIG. 14 , the strike plating process is executedon the plated portions of the suspension board 1A in the platingapparatus 230. Thus, a main plating layer 63 made of gold (Au) is formedso as to cover the side surfaces and the upper surface of the platingunderlayer 62 of the terminal portion 21 a. Thus, a main plating layer63 made of gold (Au) is formed so as to cover the side surfaces and theupper surface of the plating underlayer 62 of the terminal portion 25 a.The main plating layers 63 may be formed on the terminal portion 21 aand the terminal portion 25 a at the same time under the same platingcondition. After the main plating layers 63 are formed, the suspensionboard 1A is cleaned in the cleaning device 270.

Subsequently, as shown in FIG. 15 , the soft plating process is executedon the plated portions of the suspension board 1A in the platingapparatus 240. Thus, a main plating layer 64 made of gold (Au) is formedso as to cover the side surfaces and the upper surface of the mainplating layer 63 of the terminal portion 21 a. Thus, a main platinglayer 64 made of gold (Au) is formed so as to cover the side surfacesand the lower surface of the main plating layer 63 of the terminalportion 25 a. The main plating layers 64 may be formed on the terminalportion 21 a and the terminal portion 25 a at the same time under thesame plating condition. The thickness of the main plating layers 64 islarger than the thickness of the main plating layers 63.

The connection terminal 21 is manufactured by formation of the coverlayer 60 made of the plating underlayers 61, 62 and the main platinglayers 63, 64 on the terminal portion 21 a. Similarly, the connectionterminal 25 is manufactured by formation of the cover layer 60 made ofthe plating underlayers 61, 62 and the main plating layers 63, 64 on theterminal portion 25 a. Finally, the suspension board 1A is cleaned inthe cleaning device 280, and the suspension board 1A is dried in thedrying device 290. Thus, the suspension board 1A is completed.

(5) Effects

With the method of manufacturing the suspension board 1A according tothe present embodiment, because a hydrochloric acid electrolyticsolution is used, the plating underlayers 61 made of nickel are formedon the terminal portions 25 a, 26 a made of stainless steel and theterminal portions 21 a to 24 a and the like made of copper or a copperalloy at the same time. Thus, the connection terminals 25, 26 and theconnection terminals 21 to 24, 31 to 36 are formed at the same time. Inthis case, an increase in number of steps required for manufacturing ofthe suspension board 1A is prevented. Therefore, the cost required formanufacturing of the suspension board 1A can be reduced moresufficiently.

The connection terminals 21 to 26, 31 to 36 are formed under the sameplating condition. Specifically, the connection terminals 21 to 26, 31to 36 are formed at the same current density (that is the same voltage).In this case, the plating process can be executed on the terminalportions 25 a, 26 a, the terminal portions 21 a to 24 a and the like inthe same plating tank. Thus, the cost required for manufacturing of thesuspension board 1A can be reduced more sufficiently. Further, this moresufficiently facilitates formation of the plating underlayers 61 on theterminal portions 25 a, 26 a, the terminal portions 21 a to 24 a and thelike at the same time.

The connection terminals 21 to 26, 31 to 36 are formed by application ofa voltage to each of the terminal portions 21 a to 26 a and the likewith use of the common electrode 150. In this case, an increase innumber of components required for manufacturing of the suspension board1A is prevented. Thus, the cost required for manufacturing of thesuspension board 1A can be reduced more sufficiently.

[5] Other Embodiments

(1) While the plating method according to the present invention is usedfor manufacturing of the suspension board 1A for an actuator of a harddisc drive device in the above-mentioned embodiment, the embodiment isnot limited to this. The plating method according to the presentinvention may be used for manufacturing of another electronic product, acircuit board or the like, and may be used for another laminate 1constituted by stainless steel, and copper or a copper alloy.

(2) While the plating underlayer 62, the main plating layer 63 and themain plating layer 64 are formed on the plating underlayer 61 formed ona plated portion in the above-mentioned embodiment, the embodiment isnot limited to this. Part or all of the plating underlayer 62, the mainplating layer 63 and the main plating layer 64 does not have to beformed.

(3) While the plating underlayers are formed on the first plated portionand the second plated portion under the same condition in theabove-mentioned embodiment, the embodiment is not limited to this. Theplating underlayers may be formed on the first plated portion and thesecond plated portion under different plating conditions. For example,the plating underlayers may be formed on the first plated portion andthe second plated portion at different current densities or differentvoltages.

(4) While the plating underlayers are formed by application of a voltageto each of the first plated portion and the second plated portion withuse of the common electrode 150 in the above-mentioned embodiment, theembodiment is not limited to this. The plating underlayers may be formedby application of a voltage to each of the first plated portion and thesecond plated portion with use of separately provided electrodes 150. Inthis case, one electrode 150 may be arranged to be opposite to thestainless steel plate 2, and the other electrode 150 may be arranged tobe opposite to the conductor layer 4.

[6] Correspondences Between Constituent Elements in Claims and Parts inPreferred Embodiments

In the following paragraphs, non-limiting examples of correspondencesbetween various elements recited in the claims below and those describedabove with respect to various preferred embodiments of the presentdisclosure are explained.

In the above-mentioned embodiment, the stainless steel plate 2 is anexample of stainless steel, the conductor layer 4 is an example ofcopper, a copper alloy or a conductor layer, and the laminate 1 is anexample of a laminate. The terminal portions 25 a, 26 a are an exampleof a first plated portion or a first terminal portion, the terminalportions 21 a to 24 a are an example of a second plated portion or asecond terminal portion, and the plating underlayers 61, 62 are anexample of a plating underlayer. The electrode 150 is an example of anelectrode, the main plating layers 63, 64 are an example of a platinglayer, the suspension board 1A is an example of a printed circuit board,the connection terminals 25, 26 are an example of a first connectionterminal, and the connection terminals 21 to 24, 31 to 36 are an exampleof a second connection terminal.

While preferred embodiments of the present disclosure have beendescribed above, it is to be understood that variations andmodifications will be apparent to those skilled in the art withoutdeparting the scope and spirit of the present disclosure. The scope ofthe present disclosure, therefore, is to be determined solely by thefollowing claims.

I/We claim:
 1. A plating method including: preparing a laminate made of stainless steel, and copper or a copper alloy; and forming plating underlayers made of nickel on a first plated portion provided at the stainless steel and a second plated portion provided at the copper or the copper alloy at a same time using a hydrochloric acid electrolytic solution.
 2. The plating method according to claim 1, wherein the forming plating underlayers includes forming plating underlayers on the first plated portion and the second plated portion under a same plating condition.
 3. The plating method according to claim 2, wherein the plating condition includes a current density or a voltage.
 4. The plating method according to claim 1, wherein the forming plating underlayers includes applying a voltage to each of the first plated portion and the second plated portion using a common electrode.
 5. The plating method according to claim 1, wherein a concentration of hydrochloric acid in an electrolytic solution is not less than 60 ml/L.
 6. The plating method according to claim 1, further including forming plating underlayers made of nickel on plating underlayers formed on the first plated portion and the second plated portion.
 7. The plating method according to claim 1, further including forming plating layers made of gold (Au) on plating underlayers formed on the first plated portion and the second plated portion.
 8. The plating method according to claim 1, wherein the laminate is a printed circuit board in which the stainless steel and a conductor layer made of copper or a copper alloy are laminated, the first plate portion is a first terminal portion provided at the stainless steel, and the second plated portion is a second terminal portion provided at the conductor layer.
 9. A method of manufacturing a printed circuit board including: preparing a laminate including stainless steel and a conductor layer made of copper or a copper alloy; forming a first connection terminal and a second connection terminal at the laminate at a same time; forming the first connection terminal includes forming a plating underlayer made of nickel on a first terminal portion provided at the stainless steel using a hydrochloric acid electrolytic solution; and forming the second connection terminal includes forming a plating underlayer made of nickel on a second terminal portion provided at the conductor layer using a hydrochloric acid electrolytic solution.
 10. The method of manufacturing a printed circuit board according to claim 9, wherein the forming a first connection terminal and a second connection terminal includes forming the first connection terminal and the second connection terminal under a same plating condition.
 11. The method of manufacturing a printed circuit board according to claim 10, wherein the plating condition includes a current density or a voltage.
 12. The method of manufacturing a printed circuit board according to claim 9, wherein the forming a first connection terminal and a second connection terminal includes applying a voltage to each of the first terminal portion and the second terminal portion using a common electrode.
 13. The method of manufacturing a printed circuit board according to claim 9, wherein a concentration of hydrochloric acid in an electrolytic solution is not less than 60 ml/L.
 14. The method of manufacturing a printed circuit board according to claim 9, wherein the forming the first connection terminal further includes forming a plating underlayer made of nickel on a plating underlayer formed on the first terminal portion, and the forming the second connection terminal further includes forming a plating underlayer made of nickel on a plating underlayer formed on the second terminal portion.
 15. The method of manufacturing a printed circuit board according to claim 9, wherein the forming the first connection terminal includes forming a plating layer made of gold (Au) on a plating underlayer formed on the first terminal portion, and the forming the second connection terminal further includes forming a plating layer made of gold (Au) on a plating underlayer formed on the second terminal portion. 